Nonaqueous electrolyte secondary batteries such as lithium-ion secondary batteries have a high energy density as compared to other secondary batteries such as lead-acid batteries and alkaline secondary batteries, and are therefore widely used as power sources of portable devices such as mobile phones. In recent years, research and development directed to use of a nonaqueous electrolyte secondary battery as a power source of a mobile body such as an electric car is being actively conducted.
While nonaqueous electrolyte secondary batteries such as lithium-ion secondary batteries have a high energy density, they are expanded due to generation of gas therein as a result of repetition of charge-discharge and long-term storage. Such a phenomenon results mainly from generation of gas by a reaction between an electrode plate and a nonaqueous electrolyte, and attempts are made to add various additives to the nonaqueous electrolyte for suppressing the generation of gas. For example, Patent Document 1 describes a compound containing sulfur as an additive to a nonaqueous electrolyte.